stazak



June 4, 1929. B. STAZAK 1,715,393

TELEPHONE SYSTEM Original Filed Sept. 20, 1926 6 Sheets-Sheet i P i if m 1 i i i Jul/2177277 maize/5575M l4] 1, vmwM fijarnsy June 4, 1929. M. B. STAZAK 1,715,393

TELEPHONE SYSTEM Original Filed Sept. 20, 1926 6 Sheets-Sheet 2 makes/557E755.

June 4, 1929.

M. B. STAZAK TELEPHONE SYSTEM Original Filed Sept. 20, 1926 e Sheets-Sheet 5 Hams.

June 4, 1929. M. B. STAZAK 1,715,393

TELEPHONE SYSTEM Original Filed Sept. 20, 1926 6 Sheets-Sheet ,4

June 4, 1929. sTAZAK 1,715,393

TELEPHONE SYSTEM Original Filed Sept. 20, 1926 6 Sheets-Sheet 5 June 4, 1929. M. B. STAZAK TELEPHONE SYSTEM Original Filed Sept. 20, 1926 6 Sheets-Sheet 6 Patented June 4, 1929.

UNITED STATES m sses PATENT OFFICE."

MICHAEL B. STAZAK, OF CHICAGO, ILLINOIS, ASSIGNOR TO 'KELLOGG SWITCHIBOARD AND SUPPLY CO'MIPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS. I

TELEPHONE SYSTEM.

Application filed September 20, 1926, Serial No. 136,481. Renewed. October 13, 1928 My invention relates to telephone systems and has to do more particularly with common battery type systems in which the cord circuits used for interconnecting subscribers lines are of the feature type, and an object of my invention is the provision or an improved circuit arrangement for a system of the above type.

One of the features of my invention is the provision of a telephone system in which the subscribers of an exchange system are divided into groups and terminate at the exchange in a group of finder switches as calling lines, and multiple jaclrs as called lines, and to which said" lines are multipled so that when a call is initiated one of the finder switches of the group is caused to operate to seize the contacts of the calling line. 7

Another feature of my invention is the provision oi call distributing means in which a group oi finder switches have multiply connected thereto cords terminating at the di;t ferent operators positions at the exchange switchboard, so that a group of subscribers lines may, through the agency of this group of finder swi ches have access to a plurality of operators positions so that the instant subscriber initiates a call, he will be connected to anyone or" the plurality of operators at the exchange board.

Another feature of my invention is the elimination of the answering jacks of the subscribers lines terminating at the exchange board, the said lines being equipped with multiple jacks only thus permitting the lines per section to be materially increased.

Another feature of my invention is the means for controlling the busy indication at the operators position. Each position remains busy so long as its particular operator has a greater number of calls beforeher than V t load, or a load equal to the smallest any other of the adjacent operators. Means are also provided. for removing the busy indication whenever an operator has a smaller load on any operators position.

Still anotherfeature of my invention is a provision of distributing means whereby the calls are distributed among the different operators positions tobe storedand whereby as many as four calls may be stored at one position at one time, said distributing means operating in such a manner as to give each operator the same number of stored calls,

in case the operators are not keeping up with the load. This storing feature provides a definite means for checking up the speed at which the calls are being handled at any particular position.

Still another feature of my invention is the provision of a revertive tone which is connected to the sleeve of the jack of the calling line and serves as a revcrtive busy test on partly lines when a subscriber calling wishes to converse with another party on the same 1111s. The revertive busy test gives the operator establishing the connection a tone terconnecting the subscribers lines,

Fig. 3 shows the busy control and call storing means,

Figs. t and 5 show the operators sequence call selecting switches,

Fig. 6 shows an o aerators circuit and selecting switch.

Referring now more in general to my invention as illustrated in Fig. 1 I show a callingsubstation A terminating at the exchange in a line circuit L comprising a line relay LE, a cut off relayCO and multiple jacks J. The finder switch F S of my invention comprises a motor magnet MM which automatically operates when a call is initiated by the sub scriber at the substation A to step the wipers 2, 3, 4 and 5 over the bank contacts 6, 7, 8 and 9 to select the contacts of the calling line. A common starting wire 1'? is provided which is common to a group of subscribers lines which lead to a group of switches FS. bridging relay BG is provided which energizes when the calling line is seized by the switch FS to shunt the motor magnet MM to prevent further advancement of the wipers 2, 3, 4 and 5. The switching relay SW energizes upon the actuation of the relay 13G to extend the starting conductor 17 through to the next finder switch FS or the group (not the circuits.

calling lines and are Similar to the switches ES and are provided with a spring restored shaft which carries wipers 54:, 55, 56 and 57 and contacts 58 59, 60 and 61 of which there are fifty sets, which may be engaged by the wipers 5 1-, 55, 56 and 57, and to which contacts of the cord circuit C at the exchange are multipled. A motor magnet'MM is provided which steps the wipers 54. 55, 56 and 57 from one set of contacts 58. 59, 60 and 61 to. the next in search of an idle cord circuit as C. A release magnet RE is provided which when energized permits the release of the switch CFS allowing the wipers to re store. A set of oif normal. contacts 0N are provided which assume their alternate position upon the first step of the wipers oif normal and again restore to their normal position when the wipers assume their normal position when the switch .is released.

The cord circuit C as illustrated in Fig. 2 is adapted to be seized by the finder switch CPS and terminates in the exchange switchboard in a calling plugCP. The cord circuit C is provided with a cord circuit battery feed relay CUR which is energized when the cord C is seized by the finder switch CFS and a relay 85 is provided which is actuated upon the energization of the relay CCR. An energizing circuit is also established for a busy control relay BUR to prepare circuits in the operators busy control and storing circuits and in the operators sequence selecting switchcircuit. as will. be more fully hereinafter described. An operators listening relay CLR is provided to control the connection of the operators set 0 to the cord conductors of the cord C. and a calling lamp is also provided which when lighted indicates to the operator associated with the cord C of which there are a pluralitythat a call has been extended to her position and to a particular cord C as will be described in detail when describing the detail operation of A sleeve relay SL is provided which is energized when the calling plug Cl is inserted into a jack of a called lin and a busy guard relay GU is energized upon the energizationof therelay SL. A party line ringing key RE is provided and associated therewith are a plurality of ringing generators G, G, G and G for. the usual signaling purposes. A ringing control relay RCR. a *inging interrupter relay RI and a ringing trip relay RT are provided for controlling the application of ringing currents to the called line, as will be more fully hereinafter described. A calling supervisory relay SR is also provided which is energized when the called subscriber answers. A combined disconnect and storing lamp signal DSL is provided for purposes as will be more fully hereinafter described.

In the system of my invention 1 divide the subscribers lines of the exchange in groups of fifty each and I associate therewith from seven to ten finder switches FS so that each group of fifty lines may be equipped with an ultimate of ten trunks, this number of course depending upon the traffic of the group of lines to which the fifty lines are multipled. These trunks or cord circuit channels extend through cord circuit finder switches CFS which may have access to a ma-Xiu'uun of fifty cord circuits as C. This group of fifty cords is multipled to as many more cord channels as will handle the traffic.

A group of one thousand lines would be separated into twenty units of fifty lines each and under average conditions ea eh unit would be provided with seven cord channels with an ultimate provision of ten channels for each group. The twenty units of seven channels each will then have access to as many as fifty cord circuits or less depending; upon the traffic. The cord circuits are arranged to be distributed to any of the operators positions and in such a way that a position may have cord circuits from all of the groups for light tra'flic when only one or two operators are required at the board.

Referring now to Fig. 8 I illustrate three operators busy control and storing circuits f, k and 7' assumed to be associated with three operators positions F. H and J. Each circuit is similar to the others and a descri tion of the circuit 7 of the position F is sufficient. The operators busy control and storing); cir cuit- 7 is provided with four call storing rolays CA. CA CA and CA which are of the ma 7 'nal type. The relay CA will operate through a 3000 ohm resistance to ground which is placed in circuit with the rclav CA upon the energization of the relav BUR of a cord C which is seized, to extend a conn ction to the operators position The relay CA5 will operate through a 1500 ohm rcsistance to ground. but not through 3000 ohms.

relay CA through a 1000 ohm resistance to lfld which relays upon energization busy all the cords of the operators position F when a cord has been seized in this operators position.

'Referring now to Figs. 4: and5, '1' illustrate the operatofis sequence call'selecting switches SCS, SOS, SSS and SCS whichare provided four per operator. These switches, when calls are extended to the op erators position F, are providedto select the selected cord circuit to operatively connect therewith. lVhen calls are stored at an operators position as F, the switches SCS,

etc, are ope Med and restored in regular rotation. The switch SCS which is typical of all four switches with which each operators position is equipped, will be described. It is provided with wipers 129, 130, 131 and 132 which through the agency of a motor magnet MM are stepped into engagement with the contact sets 133,134, 135 and 136 to select the contacts to which the seized cord circuit is multipled. A bridging relay BG is provided which when energized connects the operators talking conductors to the cord conductors. A release magnet R1 2 isalso provided, which when energized Withdraws its retaining pawl to permit the wipers to restore to normal under spring tension. 01? normal contacts ON are also provided, which assume their alternate position upon the first step of the wipers 011 normal and are restored to their normal position upon the restoration of the wipers to normal.

In Fig. 6 1 illustrate an operators selecting switch OS which comprises wipers 170,

171, 172 and 173 which are stepped from one'contact set 17%, 175, 176 and 177 to the next through the agency'ot a motor magnet- MM to pick up the calls extended to an operators positionin the order in which they are received or stored at an operators'position. A bridging relay BG is provided which, when energized, connects the operators set through to the cord conductors. The switch is a five point switch andwhen the wipers reach the fifth set of contacts a release magnet RM is "energized'to release the wipers so that they. may again be stepped irom one contact to the next to connect the operators set 0 to the cord conductors. A

set otoii normal contacts (EN are provided which are moved to their alternate position upon the first step of the wiperso-ii normal and moved back to tl1e1r norinal position when the wlpers are restored to normal.

'The operators busy control and storing equal to the smallest load on any operators posltlon 1n the same group.

A storing feature is also provlded whereby as many as four calls may be stored in front 7 of each operator. Inthe cord circuit C as described in connection with Fig. 2 a lamp CAL is lighted when a call is extended to the operators position and indicates to-the operator at all times the number of calls stored at her position. The switches SCS, SOS, SOS and'ScS ot which there are four for each operators position also opcrate when calls are connected to an operators position, and when calls are stored the switches SCS, SCS, SCS and SCSalso operate to store the calls on the four switches SSS, SCS, SCS and SCS in their regular rotation. The operators switch OS of which there is one for each position, picks up these calls in the sequence in which they are received and stored.

aving described in general the switches and apparatus comprising the circuit arrangement of my invention, I will now describe in detail the operation otthe circuits 111 establishing a connection between a calling and a called subscriber and also the-operation of the storing and sequence selection circuitassociated with my invention.

Assuming now that the scubscriber at the substation A initiates a call, the removal of the receiver at the substation closes an en ergizing circuit for the line relay LR of the line circuitL over the line conductors. The closure of alternate contact 10 of the line relay LR closes an energizing circuit for the motor magnet MM of the finder switch FS traced from battery through the resistance 11, through the winding of the motor magnet MM, its normal contact 12, conductor 13, normalcontact 14 of off normal contacts ON, conductor 15, normal contact 16 of the switching relay SW, common starting 'conducto-r 17, 'toground. at alternate contact 10 ofthe line'relayLR. The motor magnet MM upon energizationsteps the wipers 2,.

normal contact 12, traced from battery through the resistance 11, through the winding of motor magnet MM, its normal contact,

12, conductor 13, alternate contact 14 of cit normal contacts ON, conductor. 18, normal contact 19 of the switching relay SW, conductor 20, to ground at normal contact 21 of the bridging relay BG.

The magnet M energizing, steps the wipers u u 7 n 1 i search of the calling line. The line relay LB.

2,3, 4 and 5 into engagement with the next set or" contacts 6, 7 8 and 9'and the opening of its'normalcontact 12', again allows the motor magnet MM to restore. The alternate closing and opening'of normal contact 12 of the magnet MM causes themagnet MM to energlze and deenerg1ze, thus stepping the wipers 4 and 5 over contacts 6, 7, 8 and-9 in upon energization also closes its alternate contact 22 placing aground upon the switch contact 6 associated with the calling line It over conductor 28 and when the wiper 2 en gages the grounded contact 6 associated with the callinglline a circuit is closed for the brid 'in g relay 13G traced from ground at alternate contact 22 01" line relay LR, conductor23, contact 6, wiper 2, conductor 24, normal contact 25 of switchin rela SlV conductor 26, normal-contact27 of relayBG,

' through the winding 28 of relay BG, conducwire 1 tor 29 to battery through-the resistance 11.

The low resistance path through the winding 7 28 of thejrelay BG shunts themagnet MM,

preventing furtheractuation of the. magnet MM and the relay BG upon energizing also opens its normal contact 21 to remove ground from the motor magnet MM. r

The closing of alternate contact 21 of the rela BC-Lu 3011 itsfener 'ization closes an the wipers of the switch'FS off normal; The

closing of. alternate contact 16 of the switching relay SW now extends the common'starting wire 17through the alternate contact 16 ot 'the switchingrelay SW to the starting l theqgroupiso that in the event that another subscriber of the group with which the calling subscriber A is associated initiates a call the next switch of the group will select this I calling line. The opening of normal con be described.

tact 25 of relay SW 'opens theinitial energizing c rcuit of relay 13G but a substitute circuit is established tor the same as will presently The switch FS havin seized the callin h '3 line an energizing circuit is-established for] the line'relayLR associated with the cord finder switch CFS traced from battery through its lower wind ng, conductor 34, nor mal contact 35 of the cut oil relay CO ofthe switch CFS, wiper 5, contact 9,. through the calling substation A back through contact 8 and wiper 4, normal contact 36 of relay CG, conductor 37 to ground through the upper the relay CR new deenergizes,

.wh'ich leads toth'e next switchfof winding of relay LR, The relay LR: upon energization closes its alternate contact 38 to close the substitutecircuit for relay BGwhicli may be traced from battery through theresistance11,-conductor 29, the upper Winding 28 of relayBG, the alternate contact 39 of relay 13G, conductors 40 and 41, alternate contact 38-015 relay LR, conductors 42 and 43, through the lower winding 44 ofrelay BG, conductor 45, wiper contact 7, condnctor 46 to ground through the winding of the cut otl relay CO of the line circuit L. The cut off relay CO of the line circuit L operates over the circuit just traced and opens the energizing'circuit of the line relay LR-of the line circuit L which restores to normal. The relay LR of the switch-(DES energizing closes its alternate contact 47to establish an ener- 'izing circuit for the control relayCR traced 'rrom battery through the winding of relay CR, conductor 48,:normal contact 49 of the motor magnet MM of the switch CPS, conductor 50,- normalcontact 51 of oil normal contact-s ON, conductor 52 to ground at alternate contact 47 of relay LR. The relay CR upon energization closes its alternate contact 53, establishing an energizing circuit for the motor magnet MM of the switch CFS traced from battery through the winding of magnet MM, conductor 62, alternate contact 53 or relay CR, conductor 63,-through the winding of slow acting relay G4, conductor 65, normal contact 66 of relay'67, conductor 68, normal contact 69 of relay CO, conductor 70 to groui'ld at wiper T he motorn' agnet MM energizes over this circuit and steps the winers 54, 55, 56 and into engagement with the first set of contacts 58, 59, 60 and 61 which lead cord circuit as at the main exchange. The motor magnet MM upon energization 1 contact 49 to. open the ener- 1 the control relay: and

ing of its alternate contact 53 opens thecircuitof the motor magnetldM. Ehouldthe first set of contacts engaged by the wipers '54, 55, 57 leadtoa cord circuit 211- ready. in use; the private contact new eng ed by-the wiper 55'will be grounded by instrume :talities more fully hereinafter described and another energizing circuit is established for the con '01 relay GR, traced .iromlbattery through the relay Clhnormal contact -19 of the magnet MM. a-lternatecontact. blot otlgnormal contacts ON, which assumed their oil normal position upon the first step oi? the ers 54, 55, 56and 5? "from their normal posit-ion, conductors 71 and 63,

through relay64 conductor 65, normal contact 66 of relayGT. conductor 68, normal conta'ct 69 of relay CG,jconductor 70, wiper 55 to the groun ded'busy contact 59., The relay CR energizing closes its alternate contact 53 establishing an energizing circuit for the motor magnetfMl /l, to ground at the busy and the opentact 88 is grounded contact 59 over the previously described path and the motor magnet MM again energizes to step the wipers 54, 55, 56 and 57 into engagement with the neXt set of contacts 58, 59, 60 and 61. The motor magnet MM upon energizing opens its normal contact e9 all-owing relay CR to. re store and relay CR restoring in turnopens the circuitot the motor magnet MM at its alternate contact 53. It will thus be seen that due-to the see-saw action of the relay CR and the motor magnet MM"the wipers 54, 55, 56 and 57 are stepped from one contact-set to the next until an idle set is encountered. WVhen the Wiper engages an ungrounded contact 59 no energizing c1rcuit is closed for relay CR and the relay CR remains at normal. and prevents 1 01 ther actuation of the motor magnet MM and the wipers now remain in engag ment with the idle set of contacts 58.59, 60 and 81. The relay 64 remain. ener ized during the rapid interruptions of the relay CR and its normal contact 72 remains open during the selecting operation to prevent the operation. of the cut oil relay CO. When the wipers engage an idle contact set the relay 6irestores and the closing oil its normal contact 72 closs a circuit for the cut oil relay CO, traced from battery through the winding of relay CO, conductor 7 8, normal contat 74 of relay 67, conductor 75 normal contact72 or relay 04-, conductor 7 6,

to round at alternate contact 77 of Oil nora: V I mal contacts ON The closing of alternate contact 78 of re-' l 80, conductorsfil and 7 0 togrounu at alternate con -ct '77 oi oil normal contacts "Oh The initial ener zf circuit of cut ea reope ed normal contact 74: oi relay 67,luit SUlJSiThLUlG energizing circuit is establisheil for the cut oil relay US helore it time to deenergize, as will be W we 1 1 m .1 f l e presently ocscii e 1e c osing o (lithinate contact 59 of relay CO places ground upon the private wiper which busies the engaged contact 59 toprevent any other switch. from engaging the selected contact set. The relay CO energizing opens its normal contacts and 36 thus opening the energizing circuit of the line relay LR and the relay LR restores and its alternate conopenedto open the series circuit of the relay BG of the switch FS and the cut oil relay C0 of the line circuit Lbut the closure of alternate contact of relay 67 maintains relays BG and CO energized through the now closed contact 82 of relay 67.

The relay CO upon energization closes its alternate contact 35 and 86 and extends the calling line to the selected cord circuit C of Fig. 2 and an energizing circuit is now established for the cord battery feed relay COR traced from battery through the lower Winding of relay CCR, contact 61, wiper 57, alternate contact 35 of relay CO, wiper 5, contact 9, through the calling substation A, back through contact 8 and Wiper at, alternate contact 36 oil. relay CO, wiper 56, contact 60, conductor 8 to ground through the upper winding of relay CCR. The relay CUR upon energizing closes its alternate contact 84: thus establishing an energizing circuit for the relay 85 traced from batterythrough th winding of relay 85, conductors 86 and 87 to ground at alternate contactSel of relay CCR. The relay 85 upon energization closes its alternate contact 88 connecting ground to the cut oil relay C0 of the switch CF55 which ias remained energized niouientart ly due to its slow to release construction after its initial energizing circuit is interrupted before described and the substitute circuit for CO may now be traced from battery through the relay CO', its alternate contact 89, conductor 90, wiper 54:, contact 58, conductor 9.1 to ground at alternate contact 88 relay 85, the said relay CO remaining energized until the termination of conversation.

The closing of alternate contact 92 of relay 85 establishes a circuit for the combined disconnect and storing lamp DEL, traced from battery through the lamp DSL, alternate con-.

tact 92 of relay 85, conductor 93 to ground at normal contact 9 1 of sleeve relay SL. The closing of alternate contact 95 of relay 85 establishes an energizing circuit for the busy control. relay BUR of the seized cord circuit C, traced from battery through the winding of relayiBCR, conductor 96, altcrnatecontact 950i relay85, conductor 97 to ground at normal contact 98 of the sleeve relay SL, The re,- lay BCR energizing closes its alternate contact 99, establishing an energizing circuit for the call storing relay CA of the operators busy control and storing circuit F oi": Fig. 3, which circuit F is common to this operators position F with which the cord circuit C as seized by the switch CFS is associated. The energizing circuit of the relay GA may he raced from ground through 3000 ohm resistance 100, alternate contact; 99 oi: relay BCR', conductor 101 which is common to all relays BCR of cordcircuits at the position F, through the winding of relay CA, conductors 102 and 103, normal contact 104: of the Cir the tip relay BG, Wiper 131, contact 135, conductor 163, alternate contact 161, of the relay SLR, conductors 165 and 83 to ground through the upper Winding of the relay CUB. The relay 1181 energizing closes its alternate contact 166, establi aing an energizing circuit for the starting relay traced from battery through the winding of the relay 'SG to ground at alternate contact 166 or the relay LE The relay SG upon encrgization closes its alternate contacts 167 and 168, and the closing of alternate contact 167 establishes an energiy-zing circuit for the switching relay of the operators selecting switch. OS, traced from ground at alternate contact 167 ot" the relay S51, conductor 169, contact 17 Wiper 171, conductor 178, normal contact 179 of relay 180, normal contact 181 of the relay 13G, through the low resistance Winding 182 of the'relay EG conductor 183, through the resistance 18% to battery.

. The circuit just traced through the relay BG shunts the magnet MM of the switch OS, due to the low resistance path through Winding 182 of relay BG, and prevents the magnet MM from stepping the Wipers 170, 171, 172 and 1.7 S of the switch. The relay 15G upon energization opens its normal contact lll'and a substitute circuit is-established for the said relay 13G, traced from battery through the resistance 181, conductor 183, through the windings 1.82 and 185 of the relay 136%, normal contact- 179 of the relay 186 to ground alternate contact 167 of the relay SG over the previously described path.

The closing of alternate contacts 186 and 187' of the relay 13G connects the operators andoft the cord G and the other our the operatofis set 1)- extends Si-a. -\1\ 1; W37 1! 1. 1

alternate contac .n. 01 tie relay g 173, Contact 177, conductor 1 89, throughalternate contact 160' ot the re; BG,iviper 132, contact 166, conduct '1? 162, alternate contact 161 of the relay Clilrl,

to the ring;

- strand of the cord C.

. eie

z to the switch SCS, the enct S'W causes its alternate the relay 190 of the cord C, traced from battery through the Windin g of the relay 1.80 01' the switch OS, conductor 191, Wiper 170, contact 174:, conductor-192, alternate conoi the relay S y, conductor 1416, Wiper 129, contact 183, ccnductorld'l, alternate contact 148 of the relay CLR to ground through the Winding of the relay 190 which relay energizes over this circuit, but relay- The closing of alternate contact 193 of the relay 190 closes a circuit for the call lamp CAL traced from battery through the lamp CAL to ground at alternate contact 193 of the relay 190, and the lighting of the lamp CAL notifies the operator at the position F that the call has been extended to her position and is awaiting her attention. The operators set 0 having been connected to the cord condu'ctors, as just described through alternate contacts 161 andlGd of relay CLR of the se zed cord C, the operator, noting the lighted signal. CAL, inquires the Wants of the calling subscriliier atsubstation A and assuming that it is the subscriber at the substation D that is wanted, the operator associated with the seized cord C now tests the multiple jack J of the wanted substation D as to its idle or busy condition in the usual manner by touchine' the tip of the calling plug GP to the slee oi? the jack J of the Wanted line. It the said called line is busy the relay 5100 in the operators et 0 operates over a circuit traced from battery on the sleeve of the jack 5 of the busy called line 1),.he tip of the plug GP, norrnal contact 2 1 1- of relay SL, conductor 161, normal contact 102 of relay 22S, conductor to ground through the winding oi. relay 100. 1

Should the calling substation call a party connected to the saznc line, I provide a special v such condition. I Assuming that such is the case now when the operator tests the called line by placing the tip of the plug GP to the sleeve of theinultiple j acl; of the called line the relay 4100 of the operators set operates over a circuit as previously described and from the description just given it is seen that the relay operates in either case. The closure of alternate contact 404 ot'relay 169 connects the special busy tone BO through alternate contact 19-1 oil relay 190, (which relay 190 energized when the operators O was connected to the conductor oi? the cord circuit C as previously de scribed) conductors 195 and196, alternate contact 88 of relay 85,,conductor 91, contact 58, Wiper 5 1, conductor 90, condenser 197, conductor 415, Wiper 3, contact '7, conductor 46 to the sleeve of theniultiple jack J of the calling line. This tone Which is placed upon the sleeve of the multiple acl; of the calling line and which is now being tested by the operatorextends through the tip of the plug G1 which was placed to the sleeve of the multiple jack of the Wanted line back over conductor 403 to the operatorsset O and gives the testing operator a distinctive signal apprising her of the fact that the called line is connected to the saine line as the calling line and the operator ncW asks the calling party to replace his receiver While the called subscriber is signalled. From the above description it is seen that when the operator tests a line other than one in which the called party is on the same line the relay operates and the tone B0 is connected through its alternate contact 404: but this connection is only incidental as in this case the operator receives only the customary busy cliclr in her head receiver, but in the event that the party minted is on the same line as the calling party the revcrtive busy tone. BO is transmitted through alternate contact 404 of relay 4.00 already described.

' Assuming that the line of the called sul 'scriber at D is idle the operator associated 'With the seizedcord C inserts the calling plug GP of the cord G into the multiple jack J of the Wanted substation D, thus establishing a series energizing circuit for the sleeve relay SLand thecut oft relay CO traced "from battery'through the windings 200 and 201 of relay'SL, conductor 202, norlflillCOIlhZl-Cl) 203 of relay 22S, conductor 205,

sleeve contacts of the connected plug GP and jack J to ground through the cut of? relay CO Therelay SL upon energization closes its alternate contact 206 thus establishing a locking circuit for itself traced from battery through the Winding 200 of relay SL, its alternate contact 206, conductor 202 to ground, through the cut oil relay CO over the previously described path. The relay Sli upon energization opens its normal contact at thus interrupting the initial energizing circuit ofthe combined disconnect and storing lainp'DSL, but a substitute circuit is established for the lamp DSL which may be traced from battery through the lamp DSL,

conductor 282, normal contact 233 of relay 228, conductor 23a, normal contact 229 01:

, nial contact 225 of relay SR, conductor 226,

the operator depresses the ringing key ll to signal thecalled subscriber.

noru n contact 227 of relay 228, conductor 208 to ground at alternate contact 94 of relay SL, the said lamp remaininglightedui ll.

relay Elli energizing closes its alternate contact 9 thus establishing an energizing circuit for the busy guard relay GU traced from battery through the winding of relay GU, conductors 207 and 208 to ground at alternate contact 94 of relay SL, for purposes as \i l presently be described.

Z. reopening of normal contact 98 of relay Sli opens the enei 'izing circuit ofthe relay BUR, and the relay BUR upon deenergisation opens its alternate contact 99. The opening; of alternate contact 99 0f relay BCR to this ope 'ators position ll.

upon the private con a 7 nd the release magnet lily The sleeve I of relay BC and the relay BC upon restoration opens its alternate contact 114, to open the energizing circuit of the relay PB. The

relay PB upon leenergization opens its alteroils in which the cord U position i terminates making them again I. selectable so that other ca ls may be extended I J The closing: oi aite nre contact 20;. ol the relay (ml ho .\c.ci p aces a. busy potential t ct a?) of the selected cord C which maybe traced from ground at alternate co: Lact 209 of relay (Ell, conductors 210 and 211 to the private ontact 59, thnsprevcnting any other switch C F5) from electing .iis particular cord that is now in use. The B lt upon restoration opens ts alternate contact to open the energizng circuit of? the cord listening relay CLR of the cord C, and the relay BG of the switch The relay CLR upon restoration opens its alternate Contact 148 allowing relay 190 to restore and the relay 190 restoring its alternate contact 193 opened to eil'aee the call nal lamp J aiid the opening of alternate contact 19% ol'relay 190 opens the tone contact from the sleeve of the jack of the calling line. The relay SLR upon toratioi'i also opens its alternate contacts 1' and 16% to disconnect the op'crators set from the cord conductors. The relay HG upon restoration closes its normal contact l4t0 closing an energizing circuit for the release magnet RM of the switch SCS traced from battery through the Winding of the release magnet R135 conductors 212 and 213, alternate contact 38 of relay SW, conductor 139 togron'n d at i'iormal conta rt 1 -0 o'i'" relay lift 7 now Withdraws etaining pawl from the ratchet and alpers 129, 130, 1.31 and 32 to retheir normal position.

I The relay 214 also energized upon the oration of the relay 13G", due to the clos- 1: is normal contact 1 1:0 but the cne w, on this reli has no effect on the circuit at this time. Vhen the Wipers reach their normal position the oil normal contacts ON assume their norn al position, and the openingoit alternate contact 158 of the said ell normal contacts ()N opens the lock- 'in circuit of rela SW and the o ienin of a y alternate contact 1 10 allows relay Bil to restore, and tie-openmg of alternate contact 138 of relay f opens the circuit ot the ct Rh? and the relay 21.4; \YlllCil 1 relay and magnet new restore to normal. l hon relay BS" dcenergizes, its alternate 159 and 160 are opened allowing I @ltly h il i/ to restore and the relay LR in llO lifO

turn opens the energizing circuit of the relay SG at its contact 166. The relay SG upon deenergization opens its alternate contact 167 thus opening the energizing circuit of relay BG of the switch OS, and the relay non restores. The sequence selecting switch SCS and the operators selecting switch OS are now at normal and are again ready to select another call that may be extended to the operators position F.

Returning now to the point where the operator has inserted the calling plug GP of the cord G into the jack J of the called line the operator associated with the cord C now depresses the proper ringing key plunger ot' the ringing key BK to connect the proper ringer generator frequency of the generators G, G, G or G as the case may be, to operate the call signal at the called substation D.

Assuming that the ringing generator G is the proper frequency for signalling the substation D, the operator depresses the ring ing key plunger associated with this frequency, and the depression of the said key plungger actuates the end spring 220 causing it to momentarily assume its alternate position, and the closure of the said contact 220 establishes an energizing circuit for the ringing control relay RCR, traced from battery through the winding of relay RCR, conductor 221, alternate contact 220 of the end springs, conductor 222, normal contact 228 of the ringing trip relay RT, conductor 224, normal contact 225 of the supervisory relay SR,conductor 226, normal contact 227 of relay 228, conductor 208 to ground at alternate contact 94 of relay SL- The closing of alternate contact 229 of relay RCR establishes a locking circuit for itself traced from battery through the winding of relay RCR its alternate contact 229, conductors 230 and 222 to ground at alternate contact 94 of relay 8L over the previously described path independent of the end spring contact 220. The relay RCR upon energization opens its normal contact 229 to bring about the etl accment of the lamp DSL and the closing of its alternate contact 236 establishes an energizing circuit for the ringing interrupter relay RI traced from battery through the winding of relay RI, alternate contact 236 of relayR-CR, conductor 237 to ground at alternate contact 238 of the end sprin The relay BI is energized over this circuit theinstant that the key plunger oi the select ed ringing frequency is depressed which also actuales the end springs to give the subscriber at the called substation an instantaneous first ring as will now be described. The instant that the relay R1 is energized ringing current from the generator G is impressed on the called line traced from the ungrounde-d pole of the generator G through the closed contact oi the ringing key plunger; conductan- 239, through the winding 240 of the ringing trip relay RT, conductor 241, alternate contact 242 of the relay RI, conductor 243, alternate contact 244 of the sleeve relay SL, tip contacts 01' the connected plug GP and jack J through the call bell and condenser at the called substation D, back through the ring contacts of the connected jack J and plug CP, alternate contact 245 of the relay SL, conductor 246 to battery and ground at alternate contact 247 of the relay RI. The flow of current from the generator G over the path just described gives the called subscriber at the substation D an instantaneous first ring.

When pressure is released from the key plunger of the selected frequency the end springs assume their normal position and the opening of alternate contact 238 opens the initial circuit through relay RI but the closing ofnormal contact 238 of the end springs now connects the constantly rotating interrupter I in the circuit with the relay RI through alternate contact 236 of relay BUR. The relay R1 is intermittently energized and deenergized by the interrupter I and the ringing current from the generator G is thus connected. and disconnected over the path previously described to intermittently operate the call signal at the called substation D. The closing of alternate contact 248 of-the relay RI also connects current from the generator G over conductor 249, through alternate contact 248 and conductor 250 to the tip c0nductor of the cord C and back to the calling subscriber at the substation A to give the subscriber thereat an audible revertive ringing tone which is an indication that the called subscriber is being signalled.

The subscriber at the called substation in response to the call signal removes his receiver from the switchook and should the subscriber at called substation D remove his re ceiver during a silent period the supervisory relay SR is energized over a circuit traced from battery through the lower winding of relay SR. conductor 251, normal contact 247 of relay RT (which is in a deenergized posi tion during a silent period) conductor 246, alternate contact 245 of relay SL, ring contacts of the connected plug GP and jack J, through the closed contacts of the substation switchhook at substation D, back through the tip contacts of the connected jack J and plug OP, alternate contact 244 of relay SL, conductor 243, normal contact 242 of relay RI, conductor 252, to ground through the upper winding of relay SR. The supervisory relay SR upon energization opens its normal contact 225 which. opens the locking circuit of the ringing control relay RCR and the relay RUB upon. deenergization closes its normal contacts 253 and 254 to extend thetalking circuit t e the called substation The opening o'fa'lternatecontact 286 of the relay RCR disconnects the interrupter I from the ringing interrupterrelay RI and the said relay RT re storing prevents further application of ring ing current.

Should the subscriber atthe substation D remove his receiver during a ringing period, the combined generator and battery current flowing through the winding 01 the ringing trip relay RT, causes the same to actuate, and the opening of its normal contact 223 opens the locking circuit of the ringing control relay RCR, which relay restores, and the opening of its alternate contact 236 disconnects the interrupter I from the interrupter relay RI and the said relay RI now restores to normal and prevents further application of ringing current after the called subscriber at the substation D answers in response to his call signal.

The subscriber at the substation A and the subscriber at the'substation Dare now in conversational circuit, the talking circuit being traced over the heavily marked conductors Assuming now that the subscribers at the substations A and D have finished their corp versation, they replace their receivers upon their respective switch'hooks. The replacing otthe receiver by the subscriber at the substation A opens the circuit of the relay CUR of the cord circuit C at the switchhook contacts and the closing of normal contact 84; of relay COR establishes an energizing: circuit for the relay 228 traced from battery through the winding of relay 228, conductor 2555, alternate contact 2560i relay 85, conductor 257 to ground at normal contact 84 of relay CUR. The relay 85 deenergizes upon the dencrgization of relay CCR due to theopcning of al-' ternate contact 84 but the relay 85 due to its slow to release construction holds up momentarily until relay 228 energizes.

The relay 228 upon energization closes its alternate contact 258 establishing. an energizing circuit for the relay 259 traced from battery through the Winding of relay 259, conductor 260, alternate contact258 of relay 228, conductor 205, sleeve contacts of the connected plug GP and jack to ground through the windingofthe cut otl" relay C0 of the line circuit Lr The relay 259' upon energization closes its alternate contact 261 establishing a locking circuit forthe relay 228 traced from battery through the winding of relay 228, its alternate contact 227, conductors 208 and 262 to ground at alternate contact 261 of relay 25.9. The relay 228 upon energization opens its normal contact 203 which opens the initial energizing circuit of the relay SL but a substitute circuit is established for the relay SL traced from battery through the upper winding 200, its alternate contact 206, conductors 202 and 2.70, alternate contact 271 of relay SR, conductors 27 2 and 205, sleeve contacts of the plug GP and jack J to ground through the cutoff relay CO, the said relay SL remaining energized until the called subscriber at D replaces his receiver.

The relay 85 having doenergized as before described opens its alternate contact 88 thereby removing ground from the conductor 91 which opens the locking circuit of the cut oil relay C0 of the switch CFS and allows the relay CO to restore. The relay CO upon deenergization closes its normal contact 7 8 establishing an energizing circuit for the release magnet RE of the switch CF5 traced from battery through the winding of magnet RE', conductor 2G5, alternate contact 266' of relay 67, conductor 267, normal contact 7 8 of relay CO, conductor 76 to ground at alternate contact 77 of off normal contacts ON of the switch CFS. The release magnet RE upon energization removes the retaining pawl from the ratchet allowing the wipers 54:, 55, 56 and 57 to restore to their normal position under Spring tension. lVhen the wipers have restored to normal, the of? normal contacts ON are moved to their normal position and the opening of alternate contact 77 of the off normal contacts ON opens the locking circuit oi the relay (37 which restores and the opening of alternate contact 266 of relay 67 opens the circuit of the release magnet RE which restores to normal. The cord circuit finder switch CFS is now at normal;

The relay 67 deenergizing opens its alternate contact 82 which opens the locking circuit of the relay BG of the finder switch FS and the relay BG upon deei'iergizing closes its normal contact 21 establishing an ener izing circuit for the release relay RE traceu from battery through the-winding of relay R "1, con-- ductor 268, alternate contact 269 oi relay SW conductor 20 to ground at normal contact 23'. of relay BG. The release relay RE upon energizatioirremoves the retaining pawl from the ratchet allowing wipers 2, 3, i and 5 to restore to their normal position under spring tension. hen the wipers have restored to normal the ofif normal contacts ON are restored to their normal position and the opening of alternate contact 33 of off normal contacts ON opens the locking circuit of the relay SiVuhich restore, and the openiu" oi alternate contact 2690i relay Sil opens the circuit-of the release magnet RE which restores to normal. The opening of the locking circuit of the relay also opens the energizii'ig circuit of the cut oil: relay (l0 of the line circuit L associated with the calling line A and the line circuit of the calling line A and the switch F8 are now at normal and are available for extending other connections. The opening of the series energizing circuit of the relay CO and relay 13G as before described removesthe busy potential from contact 7 engagedby Wiper 3 and the sleeve contact of the multiple jacks J associated with the calling line A so that the said line is immediatcly available as a called line and also allows the calling line to immediately recall.

The replacing of the receiver at the called substation D opens the circuit of the supervisory relay SE of the cord C at the switchhook contacts and the relay SR deenergizing opens its alternate contact 271 allowing relay SL to restore. The relay 53L upon deenergizing opens its alternate contacts 244 and 245 which opens the tip and. ring conductors of the cord and asrelay 259 is energized as be fore described to ground through the cut off relay CO the relay CO dcenergizes due to the high resistance of relay 259 placing the line relay LE again under the control of the called substation D to permit the called sul scriber at D to recall before the plug (JP is disconnected from the jack J. The dcenergization of relay SL closes its normal contact 94; closing acircuit for the combined disconnect and storing lamp DSL traced from battery through the lamp DSL, conductor 232, alternate contact 283 relay 22S, conductors 273 and 93 to around at normal contact 9% of relay SL. The lamp DSL is lighted over this circuit and signals the operator associated with the cord C that the subscriber has finished the conversation. The relay SL upon deenergizing opens alternate contact 94 thus opening the energizing circuit of the relay GU but the r lay GU is held energized to ground at alternate con tact 261 o't' relay 259. The relay GU is thus maintained energized and continues to connect ground to the test conductor 211 which leads to the test contacts 59 of the switch CFS to which the cord circuit is niultipled, thus any other finder switch CFS is prorentcd from selecting the cord C that is still connected to the called line D. The operator notinp the lighted disconnect signal DSL now withdraws the plug C]? from the jack 3 of the called line \vhiclrallows relay 259 to deencrgize. The relay 259 upon deenergizing opens its alternate contact 261 which allows relays GU and 228 to restore to normal. The relay 228 upon ,deencr izing opens its alternate contact 233 to ei'l ace the signal SL. The relay GU upon dcenergization opens its alternate contact 209 removing ground from the test conductor 211, thus redrawing; the busy potential torender the cord and storing circuit of Fig. 3 and the operators sequence selecting); circuits of Figs. 4, 5 and 6, we will now describe more in detail the operation oi? the circuits when calls are being stored before the different operators positions illustrated in Fig. 3, and the method. of selecting the calls iii-sequence by means of the operators sequence selecting circuits, illustrated in Figs. l, 5 and 6.

Assuming now that the operators at posi tions F, H and J are idle and that the first call COllllllQ' in has selected the cord C associated with the operators position F, as in the previous description, relays CCP, and BUR are energized; and the closure of the alternate contact 99 of relay BUR of the selected cord 0 connects the 53000-011111 resistance 100 from ground to battery through the relay CA 01'' the operat ons position l? over a path previously describei'l. lhe relays BC and PB are also operated as previously'described and the relay PB closes its alternate contact 116 to cause the operation of the group busying relays BU which relays BU operate to place a ground or busy potential upon the balance of the cords in this operators position F, as previously described in detail.

Assuming that the operator at position F does not answer this call, the second call extended to the exchange will select a cord as C in the operators position I'll. Relays CUB, and BCR oi the cord G seized in the operators position H will operate in a like manner, and the closing of alternate contact 99 of the relay BUR will connect ground through the 3000-ohm resistance through the winding of relay CA of the operatofls position H to battery at normal contact 112 of the relay BC associated with the operators position H. Relay CA operates to close an energiziup,- circuit for the relay BC, due to the closure of alternate contact 113 of the relay (a r. The relay DC energizing in turn establi. s an energizing; circuit for the relay PB traced from ground thri'iugh alternate contact 114 oi the relay BC, and through the winding 115 oi the relay PB to battery.

Relay PB" energizing its alternate contact 116 is closed to establish an energizing circuit tor the group busying relays Bil associated with the operators position H, which relays BU operating close their alternate contacts, placing a. ground or busy potential upon the rest or the cords in this position lrl,

Assuming that the operators at positions F and H do not answer either call and that athird call is initiated it is extended to the )OSlblOIl J, the only position having cords notbusy. The relay CA associated with the position J will operate from ground through the 3000-ohm resistance of the selected cord C of the operators position J, through the winding of the relay CA to battery at normal contact 112 of relay B0 of the position J. The closing of alternate contact 113 of relay CA closes a circuit through relay BC which will be energized to in turn close a circuit for the relay P13 traced from battery through its upper winding 115 to ground at alternate contact 11% of relay BS The closure of alternate contact 300 if il J closes a circuit through the lower winding 301 of relay PR traced from battery through the winding 301 alternate contact 300 conductor 302, alternate contact 303 of the relay BC of the position H, alternate contact 303 of the relay BC of the position F to ground. The closing of alternate contact 1 of the, relay BC at the position J now closes a circuit through the lower winding 301' of the.

relay PB of the position H, thecircuit being traced from battery through the lower winding 301, alternate contact 300 of tie relay BC, conductor 305, the alternate contact 2-300 of the relay BC ot the position F, conductor 307, alternate contact 30% of relay B6 of position J to ground. I i

The closing of alternate contact 300 of the d relay B6 of the position J closes circuit through the lower winding 301 of the relay PB. otthe posltion F, traced from battery through the winding 301, alternate contact 300 of the relay BC of the position F, conductor 308, alternate contact 300 oi": the relay BC ofthe position H, conductor 309, alternate contact 306 of the relay B0 of the position J to ground. The circuits through the lower windings 301, 301, 301 of the relays PB, PB and PB of the positions F, l. and J bring about the de-energization or" the said relays the respective positions F, H and J, due to their differential construction, and the opening of their alternate contacts 116, 116 and 116. removes the ground from conductors 117, 117 and 117 to open the circuits of each of the groups of busy relays BU asso ciated with the positions F, H and J, thus removing the busying ground from all the cords in these positions not in use. Assunu ing that the operators at positions F, H and J have not answered any one of the three calls and a fourth call comes in, and assuming that position F is selected, the relay BGR- of the seized cord circuit C associated with theposition F that is extending the call to the operators position F closesits alternate contact 99, placing an additional 8000-ohm resistance 100 in multiple with the common conductor 101, and the two 3000-oh1n' resistances 100 placed in multiple with the conductor 101 re duce the resistance to 1500- ohins, and as the relay CA will operate tl'irou-gh 1500 ohnis'the relay CA ot'the position F operates over a eircuittraced from battery at normal contact 112 of the relay BC, conductors 111, 110 and 109, normal contact 108 of the relay B6 conductors 107 and 106 through the winding of the relay CA conductor 102, through the windingof the-relay GA and ever conductor 101 to ground at the alternate contacts 09 of the two relays BCR of the cord circuits (.3 that are selected, now that another call has been extended to the operators position F. T he relay CA upon energization closes its alternate contact 113 to bring about the euergization of relay RC and the relay RC in turn closes a circuit for the relay PB", and the relay PB upon energization closes its alternate contact 110 to again establish an energizing circuit for the busy group relays BU associated with the position F, which re ays upon encrgization again close their alternate contacts to busy the remaining cords at the operators position F.

The fifth incoming call will be extended to position H and cause the energization oil the relay CA associated with the position H, the said relay CA energizing in a similar manner to that described in connection with relay CA of position F, whereby tworesistances 100 placed ininultiple with the conductor 101 permit the relay CA to energiae for the same reason as described in connection with relay CA of position F. The relay CA upon energization closes its alternate contact 113 and brings about the energization oi? the relay BC, which in turn closes a circuit for rblay PB, and the relay PB upon euergization closes its alternate contact 110 to opera to the busy group relays BU associated with the position H to cause the remaining cords at the position H to be husied against selection.

The sixth incoming call will be exteiulcd to the position J to cause the relay C to he energized in a manner obvious from the preceding explanation, and relay ,lA in turn brings about the energization of the relay BC through its alternate contact 113. Rd lay upon energization closes its altcr nate contact 1M to close a circuit through the upper winding of the relay PB, but the relay PB, due to the dillerential construction, restores to normal as a circuit is also closed through its lower winding which hrin s about the dr-cncrgization oi? l'liis relay PB. The diticrcut PB and ll i' ot the FOSllTlOllu F and ill also restore to normal due to circuits being closed through their lower windings over circuits correqaonding to those described in connection with the first three calls that were stored at the operators positions F, H and J The relays PB", PB and PB open their alternate contacts to perinit the dc-enorgizati on of the busy group rclays BU associated with the three positions F, H and J, and each group relays BU associated with. said position will cause the remaining cords in the positions 13, H and J to again test idle.

Assuming that none of the six calls thus far extended to the positions F, H and J have been answered, a seventh call coming in will again be extended to the position F, and as relays BC and BS of the position F are enerzal re ars relay PB the relay remains at normal. cuits are also established through the lower gized, the normal contacts 104 and 108 of the relays BC' and BC are opened and such seventh call will be extended to a cord circuit C at the position F and bring about the encrgization of the relay BCR at that cord, and the closing of its alternate contact 99 will place another 3000-ohm resistance 100 in multiple with the other two resistances 100 of the two other cords C that havebeen connected. The resistance between conductor 101 and ground being 1000 ohms relay CA energizes and brings about the energization of the relays BC and PB. The relay PB energizing its alternate contact is closed to energize the group busying relays BU, which relays BU in turn busy the remaining cords at the operators position F.

An eighth call coming in will operate the relay CA in a like manner as described in connection with relay CA, and the relay CA upon energization brings about the energization of the relays B6 and PB and the closing of the alternate contact of the relay PB operatesthe busy relays BU associated with the position H, busying all the remaining closed upon the energization of relay BC and due to the differential construction of the Cirwindings oi the relays PB and PB of the positions F and H upon the energization of relay BC of position J, and due to their di'il'erential construction they restore, and due to the opening ot' the alternate contacts of the 1'&lii -,S PB and PB and PB at the positions F, H and J, the circuits of each group of group busying relays BU will be opened and permit the deenergization of their associated group busying relays BU to remove the busy t om the remaining cords at the positions F, H and J.

A tenth call coming in will be extended to the operators position F, and a cord circuit C having been seized in the operators posi-:

tion F, a "Fourth 3000ohn'1 resistaneelOO is coiniected in multiple with the other three noes 100 of the other cords at the operition F to further reduce the resistance connected to the common conductor 101, thus causing the relay CA to energize and the relay CA energizing brings about the cnergization of the relays BC and BP", and the relay BB upon energization closes its alternate contact to energize the group bnsying relays BU associated with the position F to busy the remaining cords at the operators position F.

An eleventh call coming in will be extended to the operators position H, and the relay CA is energized in the same manner as relay CA", and the relay CA in turn will bring about the energization of the relays BC and PB, and the relay PB in turn will bring about the energization of the group busying relays BU associated with the position H to busy the remaining cords in this position.

A twelfth call coming in will be extended to the operators position J and cause the energization of the relay CA in the same manner as described in connection with relay CA and CA, and the relay CA upon energization will bring about the energization of the relay BC. No energizing circuit is eliected for the relay PB of the position J as a circuit is also closed through its lower winding, and due to its differential construction relay PB deenergizes. Relays PB and PB at the positions F and H are also deenergized due to the circuits being established through the lower windings upon the energization of relay BC of position J, and due to their dillerential construction they restore to normal. and the opening of their alternate contacts will permit the deenergization of the group of group busying relays BU of the re spective positions F, H and J, removing the busy from the remaining cords at the operators positions.

For a simple understanding and description of the circuit operation, I have in the -li'oregoing assumed that the calls came in to the various positions in regular sequence, that is, 1, 2, 8, order, top level, then 1, 2, 3 order, second level, and so on down to the bottom level. It is however, obvious that in actual practice such regular sequence would rarely, if ever, occur. Now that the regular order of operation is disclosed it is apparent that the organization of the system as a whole assures merely the desired method of operation, which is that each operator of the group F, H and J has one stored call (it making absolutely no difference in the circuit organization which of F or H or J got the first call or the last call) before a second call can be stored before any operator of the group. Furtherinore, it is indifferent to the circuit organization whether the second call stored at one position happens to strike F, H or J. The organization of circuits, however, does guarantee to each operator that she will not have a third call stored against her until the operators each have two awaiting attention. In other words, the calls will in actual practice be stacked up at hazard, as one might say, except that no operator can ever have more than one call more than any other operator.

In the description thus far we have assumed that twelve calls have come in and none of them were answered so that each of the jposition's F, H and J have four calls stored in each position. 7

Four cords C have been seized in each operators position F, H and J, as just described, and from the previous description, it is remembered that relays GCR, and BGR are energized as soon'as switch CFS seizes thc'cords C in the positions 1*, H and J. The energization of each of the relays 85 otthe cord circuits C will bring-about the lighting ot'the disconnect and storing lamps and theglowing -ot the tour lamps DSL at each operators position F, H and J shoe-"s that tourcall-s are stored at each of the operators positions. "When theiiirst call was stored inthe operators position Fthe relay BUR was energized, andthe closure of its alternate contact otthe relay BUR closes energizing circui't tor'the'motor magnet Mlti of the sequence call-selecting swltch $68, of which there are tour for each operators'position, and the motor magnet MM stcps'the wipers 129,130,131 and 132 into engagement with the ct-ot'contacts 138, 134:, 185 'and136 which lead to the seized co'rd'C. The second call stored at the position F causes the relay BGR of the second seized cord C 'to close its alternate contact 120 to establisha'n energizing circuit for the motor magnet MM ot' the switch SSS associated with the operators position F, the circuit bemg traced from battery through the resistance 122, through the winding of the magnet MM its normal contact 12,8",normal contact 12 1: of the elf-normal contacts 0N conductor 125, normal contact 126 of the relay SW over conductor 315, through alternate contact 126 of relay'SlV of switch $653, common starting conductor SA, normal contact .127 of relay'CLlt, conductor 128 to ground at alternate co'ntact120 otthe relay BOB of the cord C that was seized in extending the second call to the operators position F.

The mbtor magnet MM of the switch SCS is energized over this-circuit and steps the wipers 129, 130, 131 and 182 into engagement with the first set or contacts 133, 134,135and 136. Upon the first step of the switch wipers cit normal, normal contact 124 of the oil normal contacts-ON is moved to its alternate position and a substitute encrgizing circuit is established for the motor magnet .MM, traced from battery through the motormagnet MM its normal contact 123, alternate contact 12 1 oi the off-normal contacts 0N conductor 137, normal contact 138, conductor 139 to ground at norinalcontact 1 10" of the relay B66 The inovtor in agifihhllhf steps the wipers 129, 130, 131 and 132 from one contact set 183, 134, and 136tothe next,.and when the wiper 129 engages the grounded contact 133 which is groundedthrough alternate contact 121 of the relay BUR of the cord C, an energizing circuit is established for the relay 13G from the said ground at alternate contact 121 of the relay BCR ol' the cord C that was seized in extending the second connection to the operator at position F, through contact 133, wiper 129, normal contact otthe relay till conductor lid, normal contact 1 13 ofthe relay 13G", through the winding 142 of the relay 13G, conductor 14:1, through the resistance 122 to battery. The circuit through the relay BG" shunts out the motor magnet MM 01 the switch SCS and prevents further stepping otthe wipers 01" the switch.

The closing of alternate contacts 159 and 160 of relay RG brings about the euergization otthe line relay LR, andthe line relay LR in turn closes an energizing circuit for the relay SG. The closing ot' alternate con tact 1 10" of relay BG closes circuit for the relay S1 7 traced from battery through the winding of relay Si l, conductor 156, to

ground at alternate contact 140 oi the relay 13G; the relay Sl t then closes a locking circuit for itself through its alternate contact 157 to ground at alternate contact 1538 of ol f-normal contacts ON. The closure of alternate contact of relay BG closes a loclrin circuit for itsel'l traced from battery,

conductor 141, through its upper winding 142, its alternate contact 150, through its lower Winding 151', wiper 130, contact 134;, through. th winding of the relay SLR of the cord C that is seized to extend the second connection to ground at alternate contact 155 of therelay' BCR of the second cord seized.

The third call having bcenextcnded to the operators position F causes the relays CCR,

85 and BUR ot the said cord C toeneigizc, and the closing of alternate contact 120 0.1? relay BCR of this third'cord C establishes a circuit for the motor magnet MM. of the switch SCS traced "from the ground that was placed on the starting conductor SA,

due to the closing of alternate contact 120 of the relay BCR of the third cord, through alternate contact 126 of the switch SCS, over conductor 815, through alternate contact 126 of the relay SlV of the switch $03, over conductor 316, through normal contact 126 of the relay SW of the switch SCS conductor 125 normal contact 12 1 oi? the ofi-normal contacts ONfinornial contact 123 of the magnet M'li l, through the winding of the lnotorn'iagnet MM, to battery through the resistance 122 Thelnotor magnet MM steps the wipers .129 131 and 132 into engagement with the first set of contacts 12 3 134 ,135 and 136 and the operation of the switch SCS is the same as described in connection with the switch 'SCS. .Vhen the wiper 129 engagesthe grounded wiper 13$ 2 

